Zimbabwe Lawyers for Human Rights said on Tuesday, Fidelis Mudimu, a manager with the group's Counselling Services Unit, and two senior staffers had been picked up in a police raid together with two colleagues.
"The three were part of the five members of the Counselling Services Unit staff who were picked up on Monday afternoon when about 20 police officers raided their offices," the group's spokesperson Kumbirai Mafunda said.
"Their two colleagues were released on Monday but the three were detained without charge. They are certain to endure another night in custody. Lawyers are preparing to file an urgent application in the high court challenging their arrest and continued detention."
The group's Counselling Services Unit offers medical and psychological assistance to victims of organised violence.
Mafunda said the three detained staffers had not been charged but that police had hinted they intended to take them to the second city of Bulawayo, where the police alleged the three defaced some property.
The arrests came after police raided the offices of Gays and Lesbians of Zimbabwe twice in August, saying the organisation had "pamphlets and fliers with information that promotes homosexuality for distribution".
Authorities in Zimbabwe have in the past threatened to revoke registration for NGOs deemed to be opposed to veteran President Robert Mugabe's policies.
In the latest raid the police said they were searching for "material that defaces any house, building, wall, fence, lamp post, gate, elevator without the consent of the owner or occupier thereof."
They seized a computer and some documents from the CSU offices. – Sapa-AFP